The present invention pertains generally to the preparation of naphthalocyanine compounds. More particularly this invention relates to a method for preparing naphthalocyanine compounds from cyclosiloxanes, which naphthalocyanine compounds are useful in the information layer of optical recording media.
Siloxane containing compounds are known and have been recognized as possessing great thermal stability and intense color. Because of their high thermal stability and intense color, siloxane polymers could prove useful in a wide variety of applications, e.g., coatings or dyes.
For example U.S. Pat. Nos. 4,131,609 and 4,132,842 describe silicon phthalocyanine-siloxy polymers of the general formula PcSi(OSiR'Ph(OSiR".sub.2).sub.r X).sub.2 and (PcSiOSiR'Ph(OSiR".sub.2).sub.n OSiR'PhO).sub.x. It is noted in the background of U.S. Pat. No. 4,132,842 that "siloxy monomers" containing a phthalocyanine nucleus would be useful as dyes, coatings, and toughening agents for highly thermally stable resins except that the known siloxane-phthalocyanine copolymers are insoluble, nonmeltable, and noncrosslinkable. The insolubility of the siloxane-phthalocyanine copolymers seriously limit their workability and usefulness as coatings. The synthesis of siloxane-phthalocyanine copolymers having high solubility in organic and polar solvents is apparently accomplished by the use of siloxane-phthalocyanine disilanols or bis(dialkylamino)siloxanes with specific co-monomers having both phenyl and alkyl substituents on the silicon adjacent to the phthalocyanine nucleus
Although compounds containing siloxanes offer uncommonly good thermal stability, the backbone tends to form a helical structure which aids in the formation of cyclic siloxanes at elevated temperatures. To avoid this problem, the prior art employs a modified siloxane containing compound formed by combining siloxane copolymers with organic and inorganic groups to inhibit the reversion to cyclics through steric and/or electronic effects. This method, however, has the inherent disadvantage of lengthy and costly preparation.
Because of the potential value of such thermally stable siloxane containing compounds, it would be advantageous if useful siloxane containing compounds could be manufactured more efficiently and simply.
Siloxy containing naphthalocyanine compounds, and in particular silicon naphthalocyanine chromophores, have been suggested for use in optical media. For example, see U.S. Pat. No. 4,725,525. A more efficient and simple method for preparing such siloxy containing compounds, therefore, would be of great benefit to the art.
Accordingly, it is an object of the present invention to prepare a siloxane containing compound more directly, efficiently and inexpensively.
It is another object of the present invention to provide a more efficient and cost effective process for preparing a naphthalocyanine compound containing a polysiloxane moiety.
Yet another object of the present invention is to provide a method for producing a polysiloxy containing naphthalocyanine compound which exhibits excellent optical recording properties and a high level of solubility in organic solvents.
These and other objects, as well as the scope, nature, and utilization of the invention, will be apparent to those skilled in the art from the following description and the appended claims.